Synthesis of TiO₂ photocatalyst thin film by solvothermal method with a small amount of water and its photocatalytic performance

Colloidal solutions containing nano-sized TiO₂ particles were successfully obtained by adding a small amount of water and employing solvothermal method. A thin film obtained from this colloidal solution (Cat. 2) exhibited much better properties than another film obtained via a sol-gel method (Cat. 1). The former had smaller and more uniform TiO₂ particles than the latter; it also had the anatase structure even after drying at 200°C; a much thinner film of Cat. 2 could be obtained and this film could remain stably attached on a silicon wafer or on a pyrex plate after a thermal treatment. Cat. 2 coated on a γ-alumina exhibited excellent performance for photocatalytic decomposition of CHCl₃ under UV-light with O₂ bubbling (90% conversion in 10min), when comparing with a result obtained without the catalyst (70% conversion after 1h).